31results about How to "Eliminate overvoltage" patented technology

An electronic ballast for at least one gas discharge lamp (LA), preferably for a fluorescent tube, having a rectifier circuit (2) connectable to a supply voltage source, a smoothing circuit (3) connected to the output of the rectifier circuit (2) for generating an intermediate circuit voltage (UZ), and an inverter (4), fed with the intermediate circuit voltage (UZ), to the output of which a terminal for the load circuit (5) containing the lamp (LA) is connected, and an overvoltage monitoring device which monitors the supply voltage (U0) delivered to the electronic ballast, whereby in the event that the supply voltage exceeds a predetermined nominal value (Ui,max), an optically or acoustically perceptible warning signal is issued.

The invention relates to a device (2) for limiting an overvoltage in the DC link (18) of a traction power converter. The inventive device (2) comprises two interruptible semiconductor switches (T7, T8) that are electrically connected in series, an inductor (48), a double-layer capacitor (50), and a resistor (54) which can be connected by means of a switch (S1). The inductor (48) and the double-layer capacitor (50) are electrically connected in series while said series connection is connected between an interconnection point (46) of the two interruptible semiconductor switches (T7, T8) and a negative conductor rail (20) of the DC link (18). Additionally, the connectable resistor (54) can be electrically connected parallel to the double-layer capacitor (50), resulting in a device which is structured in a particularly simple manner and by means of which overvoltages occurring in the DC link (18) of a traction power converter can be suppressed.

The invention discloses a low voltage crossing double-fed blower fan, and a low voltage crossing method of the same. The low voltage crossing double-fed blower fan includes a motor body, a three phase transformer (5), a first current transformer (1), a chopper (2), an energy storage module (3) and a current transformer set, wherein when detecting that the voltage of a grid connection point drops, an output voltage reference signal of the first current transformer can be obtained through processing of a grid voltage signal; and then the reference signal passes the voltage outer ring controlled by PI and the current inner ring controlled by an internal model, so that a control signal of the first current transformer is obtained and control of the output voltage of the first current transformer can be realized. The low voltage crossing double-fed blower fan solves the problem that when the grid voltage drops deeply, the double-fed blower fan cannot realize low voltage crossing, can effectively control the a double-fed blower fan stator side current transformer, a rotor side current transformer and a direct current capacitor overvoltage during the grid malfunctioning period, and can improve the low voltage crossing capability of the double-fed blower fan.

The invention discloses an arc grounding overvoltage limiting device applied to a medium-voltage power distribution system, which includes a single-phase fast electronic switch controlled by an intelligent controller and a high-energy nano-zinc oxide energy-absorbing arc extinguishing device; the single-phase fast electronic switch is three Only, the main circuits of the three single-phase fast electronic switches are connected in a star shape, and the three high-voltage terminals are respectively connected to the three-phase busbar of the system, and the other ends are connected in parallel to the upper end of the high-energy nano-zinc oxide energy-absorbing arc-extinguishing device The high-energy nano-zinc oxide energy-absorbing arc-extinguishing device is composed of a high-energy zinc oxide linear resistor, a nano-damping absorber, a high-energy zinc oxide non-linear resistor and a high-voltage thyristor, wherein the high-voltage thyristor is connected in parallel to the high-energy zinc oxide Linear resistors and nano-damping absorbers at both ends. Compared with the prior art, the invention can effectively limit the single-phase intermittent arc grounding overvoltage in various operating modes of the 3-35KV neutral point non-directly grounded power grid.

Provided is a voltage resisting type isolation transformer box of a traction substation. The box comprises a box body, a voltage resisting type isolation transformer, two same fuses and two same surge protectors. The voltage resisting type isolation transformer, the fuses and the surge protectors are installed in the box body. Primary-side power supply input two ends of the voltage resisting type isolation transformer are connected with power output two ends of a low-voltage power distribution cabinet of the traction substation through wires. Two ends of the surge protectors are connected with primary-side two ends of the voltage resisting type isolation transformer through wires. Other ends of the two surge protectors are connected with the box body through wires. Two ends of the two fuses are connected with auxiliary-side power supply output two ends of the voltage resisting type isolation transformer through wires, and other ends of the two fuses are connected with power supply input two ends of electrical parts in an operation mechanism box of an electric isolation switch of an electrical railway contact network power supply system. According to the invention, damage to devices in the low-voltage power distribution cabinet of the traction substation caused by overvoltage is avoided and the box has profound prospects.

The invention provides an electric energy security intelligent detection and control device which solves the problems that an existing electric energy detection and control device is single in function and cannot achieve intelligent detection or control, and relates to the technical field of monitoring and control of an electric system. The device comprises a voltage detection circuit and a resonance elimination and arc extinction circuit. The voltage detection circuit is connected with the resonance elimination and arc extinction circuit in parallel and then is connected with a disconnecting switch in series; the voltage detection circuit comprises a breaker, a voltage transformer and a control device, and the breaker, the voltage transformer and the control device are sequentially connected in series; the resonance elimination and arc extinction circuit comprises a breaker, a touch switch and a state detection protector, and the breaker, the touch switch and the state detection protector are sequentially connected in series; the disconnecting switch, the breakers, the touch switch, the control device and the state detection protector are respectively connected with a microcomputer controller. The intelligent detection and control device is reasonable in design and complete in function; the intelligent detection and control device can be provided for the electric system, and management of an automatic system can be facilitated. Real-time detection and automatic control are achieved through the microcomputer controller, overvoltage, resonance vibration and arc light grounding phenomena in the system can be eliminated, and real-time monitoring and feedback regulation can be achieved.

The invention provides a distribution transformer gear discrimination method based on least square regression. The method comprises the following steps: acquiring a distribution transformer voltage, and carrying out filling on missing data in the distribution transformer voltage through a Lagrange interpolation method so as to obtain target data; drawing a voltage curve according to the target data; performing least square regression on the voltage curve, and setting a first equation; establishing a function of parameters in the first equation, and calculating an expression of the parameters about the first equation so as to obtain a second equation; and calculating a least square voltage regression mean value according to the second equation, and performing archiving based on combination with a distribution transformer gear selection principle. According to the method, firstly, missing data are filled by using the Lagrange interpolation method, then a least square regression straight line is obtained by using distribution transformer outlet voltage, and finally, the least square regression mean value is calculated to realize matching with the gear to which the least square regression straight line belongs. Experimental results show that the provided discrimination method can accurately carry out gear affiliation and has certain reliability.

The invention discloses an uninterruptible power supply intelligent overvoltage protection device, and belongs to the technical field of power electronics. Overvoltage energy is absorbed by a supercapacitor C through a transformer TK and a diode D, and an auxiliary control circuit is adopted in a matched mode. The overvoltage protection device can be installed on a power supply bus and is used foreliminating lightning stroke overvoltage and internal overvoltage of a high-voltage power grid in various working conditions so as to achieve the effects of stabilizing the power grid, protecting theequipment, improving the reliability of the system and the like.

An RC circuit for eliminating contactor coil surge in a switch cabinet relates to the technical field of switch cabinet control circuits. The utility model is characterized in that it comprises a resistor, an electrolytic capacitor and a power frequency AC contactor, the resistor and the electrolytic capacitor are connected in series, and the series circuit formed by the resistor and the electrolytic capacitor is connected in parallel with the power frequency AC contactor. The invention has a simple structure, can effectively eliminate the overvoltage generated by the contactor coil switch, and increases the safety, stability and continuity of the circuit.

An RC circuit relates to the technical field of a switch cabinet control circuit. The RC circuit is characterized in that the RC circuit comprises a resistor, an electrolytic capacitor and a power frequency AC contactor, wherein the resistor is connected in series with the electrolytic capacitor, and a series circuit formed by the resistor and the electrolytic capacitor is connected in parallel with the power frequency AC contactor. The RC circuit is simple in structure and can effectively eliminate overvoltage generated by a contactor coil in the on and off process, and thus circuit safety, stability and continuity are enhanced.

The protecting apparatus is composed of the signal input sampling amplifying circuit the logic circuit, the execution protecting circuit. Through the sampling resistance, the voltage input is parallel connected with the input of the signal input amplifying circuit is connected with the input of the logic circuit, the output of the logic circuit is connected with the input of the execution protecting circuit.

A rheostat circuit for eliminating contactor coil surge in a switch cabinet relates to the technical field of a switch cabinet control circuit. The rheostat circuit is characterized in that the rheostat circuit comprises a rheostat (1) and a contactor (2), wherein the rheostat (1) is connected in parallel to the two ends of the contactor (2). The rheostat circuit is simple in structure and can effectively eliminate overvoltage generated by a contactor coil in the on and off process, and thus circuit safety, stability and continuity are enhanced.

A rheostat circuit for eliminating coil surge relates to the technical field of a switch cabinet control circuit. The rheostat circuit is characterized in that the rheostat circuit comprises a rheostat (1) and a contactor (2), wherein the rheostat (1) is connected in parallel to the two ends of the contactor (2). The rheostat circuit is simple in structure and can effectively eliminate overvoltage generated by a contactor coil in the on and off process, and thus safety, stability and continuity of the circuit are enhanced.